// Transparency 
// by REAS <http://reas.com> 

 
PImage a, b; 
boolean once = false; 
int[] buffer; 
float bufferOffset, newBufferOffset; 
 
void setup() 
{ 
  size(200, 200); 
  buffer = new int[width*height]; 
  bufferOffset = newBufferOffset = 0.0; 
  a = loadImage("construct.jpg");  // Load an image into the program 
  b = loadImage("wash.jpg");   // Load an image into the program 
  framerate(60); 
} 
 
void draw() 
{ 
  image(a, 0, 0); 
  
  newBufferOffset = -b.width/2 + (mouseX*2-width/2); 
  float distance = bufferOffset - newBufferOffset; 
  if( abs(distance) > 0.01 ) { 
    bufferOffset -= distance/10.0; 
    bufferOffset = constrain(bufferOffset, -400, 0); 
  } 
  tint(255, 153); 
  image(b, bufferOffset, 20); 
}